Biologics are commonly employed to promote bone growth in medical applications including fracture healing and surgical management of spinal disorders. Spine fusion is often performed by orthopedic surgeons and neurosurgeons alike to address degenerative disc disease and arthritis affecting the lumbar and cervical spine. Historically, autogenous bone grafting, commonly taken from the iliac crest of the patient, has been used to augment fusion between vertebral levels.
One protein that is osteogenic and commonly used to promote spine fusion is recombinant human bone morphogenetic protein-2 (rhBMP-2). Its use has been approved by the US Food and Drug Administration (FDA) for single-level anterior lumbar interbody fusion. The use of rhBMP-2 has increased significantly since this time and indications for its use have expanded to include posterior lumbar spinal fusion as well as cervical spine fusion.
Oxysterols form a large family of oxygenated derivatives of cholesterol that are present in the circulation, and in human and animal tissues. Oxysterols have been found to be present in atherosclerotic lesions and play a role in various physiologic processes, such as cellular differentiation, inflammation, apoptosis, and steroid production. Some naturally occurring oxysterols have robust osteogenic properties and can be used to grow bone. The most potent osteogenic naturally occurring oxysterol, 20(S)-hydroxycholesterol, is both osteogenic and anti-adipogenic when applied to multipotent mesenchymal cells capable of differentiating into osteoblasts and adipocytes.
One such oxysterol is Oxy133 or (3S,5S,6S,8R,9S,10R,13S,14S,17S)17-4S)-2-hydroxyoctan-2-yl)-10,13-dimethylhexadecahydro-1H-cyclopenta[a]phenanthrene-3,6-diol, which exhibits the following structures:

To synthesize Oxy133, often there are complex, multi-step chemical reactions that are difficult to carry out in a single container. For example, to synthesize Oxy133 there may be utilization of various protection reagents to protect end groups as the molecule is being synthesized. In addition, various deprotection reagents are also utilized that increase cost, reduce safety and have an adverse environmental impact. Further, the route of synthesis of OXY133 can have very low yield less than 30%.
Therefore, there is a need for a cost effective method of synthesizing Oxy133 for use in promoting osteogenesis, osteoinduction and/or osteoconduction. Methods of synthesizing Oxy133 having a high yield and improved process safety would be beneficial. Methods for synthesizing Oxy133 from endogenous starting material, which is stereoselective, would also be beneficial.